Pharmacokinetics, Pharmacodynamics, and Safety of the Dual Orexin Receptor Antagonist Lemborexant: Findings From Single-Dose and Multiple-Ascending-Dose Phase 1 Studies in Healthy Adults

Lemborexant, a dual orexin receptor antagonist, is approved for the treatment of insomnia and is under investigation for treating other sleep disorders. Here we summarize pharmacokinetic, pharmacodynamic, and safety data from 3 randomized, double‐blind, placebo‐controlled phase 1 studies: single ascending doses in healthy adults (Study 001; 1‐200 mg; N = 64), multiple ascending doses in healthy and elderly adults (Study 002; 2.5‐75 mg; N = 55), and multiple doses in healthy white and Japanese adults (Study 003; 2.5‐25 mg; N = 32). Lemborexant exposure increased with increasing dose. The time to maximum concentration ranged from approximately 1 to 3 hours for the 5‐ and 10‐mg doses. The mean effective half‐life was 17 hours for lemborexant 5 mg and 19 hours for lemborexant 10 mg. The plasma concentration at 9 hours postdose was 27% of the maximum concentration following multiple dosing with lemborexant 10 mg. There were no clinically relevant effects on next‐morning residual sleepiness (Karolinska Sleepiness Scale, Digital Symbol Substitution Test, Psychomotor Vigilance Test) for doses through 10 mg/day, indicating no effect of residual plasma concentrations on next‐day residual effects. Lemborexant was well tolerated across the doses tested. There were no clinically relevant effects of age, sex, or race on lemborexant pharmacokinetics, pharmacodynamics, or safety. These results suggest that lemborexant at doses through 25 mg provides an overall pharmacokinetic, pharmacodynamic, and safety profile suitable for obtaining the target pharmacologic effect supporting treatment of insomnia while minimizing residual effects during wake time.

Middle-of-the-night administration of sleep medication: a critical review of the effects on next morning driving ability

STUDY OBJECTIVES

Sleep maintenance problems are common, hence treatments enabling patients to fall asleep more rapidly after middle-of-the-night (MOTN) awakenings, without impairing next morning alertness, are needed. This literature review compares the effects of MOTN administration of various hypnotics on morning driving ability, a potentially dangerous daily activity under conditions of impairment.

METHODS

A literature search was conducted identifying on-the-road driving studies examining the effects of MOTN administration of hypnotics on morning driving performance. In a standardized 100-km highway driving test in normal traffic, subjects were instructed to drive with a steady lateral position and constant speed of 95 km/h. The primary outcome measure of the driving test is the Standard Deviation of Lateral Position (SDLP, cm), i.e. weaving of the car.

RESULTS

Four driving studies were identified. Driving performance after MOTN administration of traditional benzodiazepine hypnotics was not examined. Zolpidem (10 mg and 20 mg, oral immediate release tablets) significantly impaired driving in a dose-dependent manner, when tested 4 hours after MOTN administration. Also, gaboxadol (15 mg) and zopiclone (7.5 mg) significantly impaired next-morning driving after MOTN administration. In contrast, sublingual zolpidem (3.5 mg) and zaleplon (10 mg and 20 mg) did not significantly affect driving 4 hours after MOTN administration.

CONCLUSION

Driving was not affected 4 hours after MOTN administration of sublingual zolpidem (3.5 mg) or zaleplon (10 mg and 20 mg). Significant driving impairment was found after MOTN administration of zolpidem (10 and 20 mg), gaboxadol (15 mg), and zopiclone (7.5 mg).

Gender differences in pharmacokinetics and pharmacodynamics of zolpidem following sublingual administration

The effect of dose and gender on the pharmacokinetics (PK) and pharmacodynamics (PD) of zolpidem after administration of a buffered zolpidem sublingual tablet (ZST; Intermezzo®, Purdue Pharma L.P., Stamford, CT, USA) was evaluated in healthy non-elderly male and female volunteers. Subjects received a single morning dose of ZST (1.0, 1.75, and 3.5 mg) or placebo in a four-way crossover study. In male and female subjects zolpidem PK were linear, with area under the curve (AUC) proportional to dose, and apparent oral clearance and elimination half-life independent of dose. However, AUC averaged 40% to 50% higher in females than in males receiving the same dose. The gender effect was incompletely explained by body weight. In females, ZST produced PD changes consistent with benzodiazepine agonist effects, particularly at the 3.5-mg dose. For several PD variables, PD effects were significantly related to plasma zolpidem concentrations when data were aggregated across subjects. However, there was variability in response among individuals. In males, PD effects of zolpidem seldom differed from placebo regardless of plasma concentration. The findings confirm that zolpidem clearance is lower in females than in males. PD effects of zolpidem from ZST are greater in female subjects, due to a combination of higher plasma concentrations and greater intrinsic sensitivity.

Donepezil in Parkinson's disease dementia: a randomized, double-blind efficacy and safety study

Parkinson's disease dementia (PDD) is associated with cholinergic deficits. This report presents an efficacy and safety study of the acetylcholinesterase inhibitor donepezil hydrochloride in PDD. PDD patients (n = 550) were randomized to donepezil (5 or 10 mg) or placebo for 24 weeks. Coprimary end points were the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and Clinician's Interview-Based Impression of Change plus caregiver input (CIBIC+; global function). Secondary end points measured executive function, attention, activities of daily living (ADLs), and behavioral symptoms. Safety and tolerability were assessed. ADAS-cog mean changes from baseline to week 24 (end point) were not significant for donepezil in the intent-to-treat population by the predefined statistical model (difference from placebo: -1.45, P = .050, for 5 mg; -1.45, P = .076, for 10 mg). Alternative ADAS-cog analysis, removing the treatment-by-country interaction term from the model, revealed significant, dose-dependent benefit with donepezil (difference from placebo: -2.08, P = .002, for 5 mg; -3.31, P < .001, for 10 mg). The 10-mg group, but not the 5-mg group, had significantly better CIBIC+ scores compared with placebo (3.7 vs 3.9, P = .113, for 5 mg; 3.6 vs 3.9, P = .040, for 10 mg). Secondary end points-Mini-Mental State Exam; Delis-Kaplan Executive Function System; Brief Test of Attention, representing cognitive functions particularly relevant to PDD-showed significant benefit for both donepezil doses (P ≤ .007). There were no significant differences in ADLs or behavior. Adverse events were more common with donepezil but mostly mild/moderate in severity. Although the study did not achieve its predefined primary end points, it presents evidence suggesting that donepezil can improve cognition, executive function, and global status in PDD. Tolerability was consistent with the known safety profile of donepezil. © 2012 Movement Disorder Society.

The ADAS-cog in Alzheimer's disease clinical trials: psychometric evaluation of the sum and its parts

BACKGROUND

The Alzheimer's Disease Assessment Scale Cognitive Behavior Section (ADAS-cog), a measure of cognitive performance, has been used widely in Alzheimer's disease trials. Its key role in clinical trials should be supported by evidence that it is both clinically meaningful and scientifically sound. Its conceptual and neuropsychological underpinnings are well-considered, but its performance as an instrument of measurement has received less attention. Objective To examine the traditional psychometric properties of the ADAS-cog in a large sample of people with Alzheimer's disease.

METHODS

Data from three clinical trials of donepezil (Aricept) in mild-to-moderate Alzheimer's disease (n=1421; MMSE 10-26) were analysed at both the scale and component level. Five psychometric properties were examined using traditional psychometric methods. These methods of examination underpin upcoming Food and Drug Administration recommendations for patient rating scale evaluation.

RESULTS

At the scale-level, criteria tested for data completeness, scaling assumptions (eg, component total correlations: 0.39-0.67), targeting (no floor or ceiling effects), reliability (eg, Cronbach's α: = 0.84; test-retest intraclass correlations: 0.93) and validity (correlation with MMSE: -0.63) were satisfied. At the component level, 7 of 11 ADAS-cog components had substantial ceiling effects (range 40-64%).

CONCLUSIONS

Performance was satisfactory at the scale level, but most ADAS-cog components were too easy for many patients in this sample and did not reflect the expected depth and range of cognitive performance. The clinical implication of this finding is that the ADAS-cog's estimate of cognitive ability, and its potential ability to detect differences in cognitive performance under treatment, could be improved. However, because of the limitations of traditional psychometric methods, further evaluations would be desirable using additional rating scale analysis techniques to pinpoint specific improvements.

Effectiveness and tolerability of high-dose (23 mg/d) versus standard-dose (10 mg/d) donepezil in moderate to severe Alzheimer's disease: A 24-week, randomized, double-blind study

BACKGROUND

Currently approved Alzheimer's disease (AD) treatments have been reported to provide symptomatic benefit, without proven impact on clinical progression. We hypothesized that the loss of initial therapeutic benefit over time may be mitigated by higher doses of a cholinesterase inhibitor.

OBJECTIVE

The aim of this study was to determine the effectiveness and tolerability of increasing donepezil from 10 to 23 mg/d in patients with moderate to severe AD.

METHODS

This randomized, double-blind study was conducted at 219 sites in Asia, Europe, Australia, North America, South Africa, and South America from June 6, 2007, to March 27, 2009. Patients aged 45 to 90 years with probable AD, Mini-Mental State Examination score 0 to 20 (moderate to severe impairment), and who were receiving donepezil 10 mg once daily for > or =12 weeks before the start of the study were eligible. Patients (n = 1467) were randomly assigned to receive high-dose donepezil (23 mg once daily) or standard-dose donepezil (10 mg once daily) for 24 weeks. Coprimary effectiveness measures were changes in cognition and global functioning, as assessed using least squares mean changes from baseline (LSM [SE] A) scores (last observation carried forward) on the Severe Impairment Battery (SIB; cognition) and the Clinician's Interview-Based Impression of Change Plus Caregiver Input scale (CIBIC+; global function rating) overall change score (mean [SD]) at week 24. Treatment-emergent adverse events (TEAEs) were assessed using spontaneous patient/caregiver reporting and open-ended questioning; clinical laboratory testing (hematology, biochemistry, and urinalysis panels analyzed by a central laboratory); 12-lead ECG; and physical and neurologic examinations, including vital sign measurements.

RESULTS

The effectiveness analyses included 1371 patients (mean age, 73.8 years; 62.8% female; 73.5% white; weight range, 34.0-138.7 kg). A total of 296 of 981 patients (30.2%) withdrew from the donepezil 23-mg/d group; 87 of 486 patients (17.9%) withdrew from the donepezil 10-mg/d group. At study end (week 24), the LSM (SE) Delta in SIB score was significantly greater with donepezil 23 mg/d than with donepezil 10 mg/d (+2.6 [0.58] vs +0.4 [0.66], respectively; difference, 2.2; P < 0.001). The between-treatment difference in CIBIC+ score was nonsignificant (4.23 [1.07] vs 4.29 [1.07]). In post hoc analysis, LSM Delta in SIB score and CIBIC+ treatment effect at end point were greater with donepezil 23 mg/d than 10 mg/d in patients with more advanced AD compared with less impaired patients (SIB, +1.6 [0.78] vs -1.5 [0.88], respectively [P < 0.001]; CIBIC+, 4.31 [1.09] vs 4.42 [1.10] [P = 0.028]). TEAEs were reported in 710 of 963 patients (73.7%) who received donepezil 23 mg/d and in 300 of 471 patients (63.7%) who received donepezil 10 mg/d. With donepezil 23 mg/d, mild, moderate, and severe TEAEs were reported in 297 (30.8%), 332 (34.5%), and 81 (8.4%) patients, respectively; with donepezil 10 mg/d, these proportions were 147 (31.2%), 119 (25.3%), and 34 (7.2%). The 3 most common severe AEs reported with the 23-mg/d dose were nausea (9 patients [0.9%] vs 1 [0.2%] with the 10-mg/d dose), dizziness (7 [0.7%] vs 1 [0.2%]), and vomiting (6 [0.6%] vs 0). The most commonly reported TEAEs considered probably related to treatment with the 23-mg/d dose were nausea (59 patients [6.1%] vs 9 [1.9%] with the 10-mg/d dose), vomiting (48 [5.0%] vs 4 [0.8%]), and diarrhea (31 [3.2%] vs 7 [1.5%]).Thirteen deaths were reported during the study or within 30 days of study discontinuation (23 mg/d, 8 patients [0.8%]; 10 mg/d, 5 patients [1.1%]); all were considered unrelated to the study medication.

CONCLUSIONS

In this study in patients with moderate to severe AD, donepezil 23 mg/d was associated with greater benefits in cognition compared with donepezil 10 mg/d. The between-treatment difference in global functioning was not significant in the overall population. Patients with more advanced AD appeared to benefit from donepezil 23 mg/d on the assessment of global functioning, but this observation requires additional studies for confirmation. ClinicalTrials.gov identifier: NCT00478205.

Circadian rhythms and photoperiodism

The circadian timing system plays a critical role in the regulation of seasonal modifications in reproductive function. By detecting and transducing changes in the day-length (photoperiod), the neural substrates of the circadian system, including the supra-chiasmatic nuclei of the hypothalamus, trigger reproductive activity or quiescence at the appropriate seasons of the year in photoperiodic species. The circadian system also plays a role in the expression of endocrine changes that occur with seasonal breeding. Surges in luteinizing hormone secretion in female hamsters, for example, are either expressed daily during reproductive quiescence or suppressed on three out of the four days of the cycle during the breeding season. By such mechanisms a daily timer can be used in the regulation of cyclic events of much longer period.

Sleep in women across the life cycle from adulthood through menopause

Studies of sleep across the life cycle in women have utilized both survey and polysomnographic techniques, but have tended to be of small sample size with diverse methodology. As a result, definitive conclusions about the impact of the menstrual cycle and use of oral contraceptives on sleep parameters cannot yet be made. Sleep disruption during pregnancy and postpartum is nearly universal, but effective and practical countermeasures are still needed. Longitudinal studies of sleep in the postpartum period are also lacking. Menopause is associated with insomnia due to several factors including hot flashes, mood disorders and increased sleep-disordered breathing. The use of hormone replacement therapy to treat sleep and other variables is an active area of investigation. In summary, much research is required to fully elucidate the impact of the life cycle on sleep parameters in women.

Treatment of depression in women: a summary of the expert consensus guidelines

Women constitute two-thirds of patients suffering from common depressive disorders, making the treatment of depression in women a substantial public health concern. However, high-quality, empirical data on depressive disorders specific to women are limited, and there are no comprehensive evidence-based practice guidelines on the best treatments for these illnesses. To bridge the gap between research evidence and key clinical decisions, the authors developed a survey of expert opinion concerning treatment of four depressive conditions specific to women: premenstrual dysphoric disorder, depression in pregnancy, postpartum depression in a mother choosing to breast-feed, and depression related to perimenopause/menopause. The survey asked about 858 treatment options in 117 clinical situations and included a broad range of pharmacological, psychosocial, and alternative medicine approaches. The survey was sent to 40 national experts on women's mental health issues, 36 (90%) of whom completed it. The options, scored using a modified version of the RAND Corporation's 9-point scale for rating appropriateness of medical decisions, were assigned one of three categorical rankings-first line/preferred choice, second line/alternate choice, third line/usually inappropriate-based on the 95% confidence interval of each item's mean rating. The expert panel reached consensus (defined as a non-random distribution of scores by chi-square "goodness-of-fit" test) on 76% of the options, with greater consensus in situations involving severe symptoms. Guideline tables indicating preferred treatment strategies were then developed for key clinical situations. The authors summarize the expert consensus methodology they used and then, for each of the four key areas, review the treatment literature and summarize the experts' recommendations and how they relate to the research findings. For women with severe symptoms in each area we asked about, the first-line recommendation was antidepressant medication combined with other modalities (generally psychotherapy). These recommendations parallel existing guidelines for severe depression in general populations. For initial treatment of milder symptoms in each situation, the panel was less uniform in recommending antidepressants, and either gave equal endorsement to other treatment modalities (e.g., nutritional or psychobehavioral approaches in PMDD; hormone replacement in perimenopause) or preferred psychotherapy over medication (during conception, pregnancy, or lactation). In all milder cases, however, antidepressants were recommended as at least second-line options. Among antidepressants, selective serotonin reuptake inhibitors (SSRIs) were recommended as first-line treatment in all situations. The specific SSRIs that were preferred depended on the particular clinical situation. Tricyclic antidepressants were highly rated alternatives to SSRIs in pregnancy and lactation. In evaluating many of the treatment options, the experts had to extrapolate beyond controlled data in comparing treatment options with each other or in combination. Within the limits of expert opinion and with the expectation that future research data will take precedence, these guidelines provide some direction for addressing common clinical dilemmas in women, and can be used to inform clinicians and educate patients regarding the relative merits of a variety of interventions.

The Expert Consensus Guideline Series. Treatment of depression in women

OBJECTIVES

Women constitute two-thirds of patients suffering from common depressive disorders. The treatment of depression in women is therefore a substantial public health concern. High-quality, empirical data on depressive disorders specific to women are limited. As a result, there are no comprehensive evidence-based practice guidelines on the best treatment approaches for these illnesses. We conducted a consensus survey of expert opinion on the treatment of 4 depressive conditions specific to women: premenstrual dysphoric disorder (PMDD), depression in pregnancy, postpartum depression in a mother choosing to breast-feed, and depression related to perimenopause/menopause.

METHOD

After reviewing the literature and convening a work group of leading experts, we prepared a written survey covering a total of 858 treatment options in 117 specific clinical situations. Depression severity (mild to severe) was specified for most clinical situations. Treatment options included a broad range of pharmacological, psychosocial, and alternative medicine approaches. Most options were scored using a modified version of the RAND 9-point scale for rating appropriateness of medical decisions. We identified 40 national experts, 36 (90%) of whom completed the survey. Consensus on each option was defined as a non-random distribution of scores by chi-square "goodness-of-fit" test. We assigned a categorical rank (first line/preferred choice, second line/alternate choice, third line/usually inappropriate) to each option based on the 95% confidence interval around the mean rating. Guideline tables indicating preferred treatment strategies were then developed for key clinical situations.

RESULTS

The expert panel reached consensus on 76% of the options, with greater consensus in situations involving severe symptoms. For women with severe symptoms in each of the 4 central disorder areas we asked about, the first-line recommendation was for antidepressant medication combined with other modalities (generally psychotherapy), paralleling existing guidelines for severe depression in general populations. For milder symptoms in each situation, the panel was less uniform in recommending antidepressants. For the initial treatment of milder symptoms, the panel either gave equal endorsement to other treatment modalities (e.g., nutritional or psychobehavioral approaches in PMDD; hormone replacement in perimenopause) or preferred psychotherapy over medication (in conception, pregnancy, or lactation). In all milder cases, however, antidepressants were recommended as at least second-line options. Among antidepressants, selective serotonin reuptake inhibitors (SSRIs) as a class were recommended as first-line treatment in all situations. The specific SSRIs that were preferred depended on the particular clinical situation. Tricyclic antidepressants were highly rated alternatives to SSRIs in pregnancy and lactation.

CONCLUSIONS

The experts reached a high level of consensus on the appropriateness of including both antidepressant medication, specifically SSRIs, and nonpharmacological modalities in treatment plans for severe depression in 4 key clinical situations unique to women. To evaluate many of the treatment options in this survey, the experts had to extrapolate beyond controlled data in comparing modalities with each other or in combination. Within the limits of expert opinion and with the expectation that future research data will take precedence, these guidelines provide some direction for addressing common clinical dilemmas in women. They can be used to inform clinicians and educate patients regarding the relative merits of a variety of interventions.

Evaluating and managing premenstrual syndrome

Premenstrual syndrome (PMS), a common disorder in women, refers to physical and/or mood symptoms that appear predictably during the latter half of the menstrual cycle, last until menses begin, and are absent during the early part of the menstrual cycle. A diagnosis of PMS requires that the symptoms be severe enough to affect a woman's ability to function at home or in the workplace or in her relationships with others. Diagnostic assessment entails a thorough medical and psychiatric history and prospective daily ratings. Disorders such as major depression, anxiety, hypothyroidism, and diabetes must be excluded before a diagnosis of PMS can be considered. Treatment strategies include either eliminating the hormonal cycle associated with ovulation or treating the symptom(s) causing the most distress to the patient. Medical therapies are available for both treatment approaches but should be initiated only after behavioral measures have failed; the physician must also carefully weigh the severity of symptoms against the potential for adverse effects of treatment.

Premenstrual syndrome. Identification and management

Premenstrual syndrome is a legitimate illness consisting of the cyclic recurrence of symptoms (physical, mental and behavioural) in the late luteal phase of the menstrual cycle of sufficient severity to require treatment. The syndrome has a yet unknown aetiology, an uncertain and variable course, and an unidentified family history. Methods are available for diagnosis including obtaining a reliable history, thorough physical and mental examinations, laboratory tests to exclude other possible causes of symptoms, and daily prospective symptom ratings to confirm symptom patterns. Because there is no known aetiology, treatment consists of symptom management of the specific symptoms experienced, based on prospective symptom ratings.

Pediatricians and sleep disorders: training and practice

OBJECTIVE

A series of studies were conducted to investigate pediatricians' training, knowledge, and practices regarding sleep and sleep disorders in children and adolescents.

METHOD AND RESULTS

Study 1, a national survey of 156 pediatric residency programs, found that pediatricians receive a mean of 4.8 hours of instruction on sleep and sleep disorders, although the mode and median hours of instruction is 0 hours. In study 2, 88 pediatricians completing a questionnaire concerning general knowledge about sleep disorders in children and adolescents received a mean score of 71.8% (range, 40% to 93%). Pediatricians appear to know the most about developmental issues and sleep hygiene and the least about specific disorders such as narcolepsy and parasomnias. In the third study, 183 pediatricians were surveyed about their actual beliefs and practices regarding young children's sleep problems. Together, those surveyed reported that approximately 25% of their patients experience some type of sleep problem. Most pediatricians recommend behavioral interventions, although 14.8% of pediatricians report prescribing pharmacological treatments, and 48.9% inform parents that their child is likely to outgrow the problem.

CONCLUSIONS

The results of these studies support the need for more education in sleep and sleep disorders in children and adolescents within medical schools, pediatric residency programs, and the practicing pediatric community.

Pharmacologic strategies for managing premenstrual syndrome

The diagnosis and pharmacologic management of premenstrual syndrome (PMS) are reviewed. PMS refers to physical or affective symptoms that appear during the latter half of the menstrual cycle, remit during menses, and affect the woman's relationships or ability to function. Pharmacologic treatments proposed for PMS include (1) hormonal treatments that alter the menstrual cycle, (2) hormonal treatments based on specific proposed etiologies, (3) drugs that affect fluid balance, (4) inhibitors or precursors of prostaglandins, (5) nutritional supplements, (6) psychotropic medications, and (7) nonprescription preparations. The menstrual cycle can be manipulated with transdermal estrogen and cyclic oral progesterone, oral contraceptives, danazol, or gonadotropin-releasing hormone agonists with steroid hormone replacement. Psychological symptoms may be treated with fluoxetine, clomipramine, or alprazolam. Patients may be given a diuretic for fluid retention; bromocriptine, tamoxifen, or danazol for mastodynia; and nonprescription analgesics for headaches. PMS can be managed through (1) a symptom-oriented management approach or (2) modification of the menstrual cycle. Pharmacotherapy should be initiated only after simpler measures have failed, and the medication must be chosen carefully, with the severity of the impairment weighed against adverse effects of the treatment.

Cognitive and motor performance of narcoleptic and normal subjects living in temporal isolation

Six unmedicated narcoleptic subjects and nine normal controls lived in a temporal isolation laboratory for 18-22 days. They were permitted to "free-run" for the last 9-13 days. Brief cognitive and motor performance tests were repeated on average six times per subjective day. They consisted of serial search, complex verbal reasoning tasks and manual dexterity of each hand. Only minor differences in performance were found between the narcoleptic subjects and controls. Narcoleptic subjects showed mild impairment of accuracy on the search task that could be explained by occasional lapses and an afternoon dip in performance. Narcoleptic subjects also tended to perform some tasks more slowly, but the group differences were not significant. Neither speed nor accuracy of performance of narcoleptic subjects decreased over the course of the experiment. By one standard of performance, therefore, all or nearly all of the sleep need of these subjects was met by the sleep they obtained in the laboratory. That amount, in turn, did not exceed the total sleep obtained by the normal controls. Significant time-of-day effects were found in narcoleptic subjects for speed of verbal reasoning (progressive slowing over the course of the day), manual dexterity (fluctuations in speeds) and accuracy of serial search (afternoon dip). These variations in performance could not be attributed to changes in core body temperature or to occurrences of naps or meals.

Age-related differences in recovery from simulated jet lag

Six healthy young men and eight early middle-aged men were isolated from environmental time cues for 15 days. For the first 6-7 days (one or two nights adaptation, four nights baseline), their sleep and meals were scheduled to approximate their habitual patterns. Their daily routines were then shifted 6 hours earlier by terminating the sixth or seventh sleep episode 6 hours early. The new schedules were followed for the next 8 or 9 days. Important age-related differences in adjustment to this single 6-hour schedule shift were found. For the first 4-day interval after the shift, middle-aged subjects had larger increases of waking time during the sleep period and earlier termination of sleep than young subjects. They also reported larger decreases in alertness and well-being and larger increases in sleepiness, weariness and effort required to perform daily functions. The rate of adjustment of the circadian core temperature rhythm to the new schedule did not differ between groups. These results suggest that the symptoms reported by the middle-aged subjects may be due mainly to difficulty maintaining sleep at early times of the circadian day. The compensatory response to sleep deprivation may also be less robust in middle-aged individuals traveling eastbound.

Age-related differences in recovery from simulated jet lag

Six healthy young men and eight early middle-aged men were isolated from environmental time cues for 15 days. For the first 6-7 days (one or two nights adaptation, four nights baseline), their sleep and meals were scheduled to approximate their habitual patterns. Their daily routines were then shifted 6 hours earlier by terminating the sixth or seventh sleep episode 6 hours early. The new schedules were followed for the next 8 or 9 days. Important age-related differences in adjustment to this single 6-hour schedule shift were found. For the first 4-day interval after the shift, middle-aged subjects had larger increases of waking time during the sleep period and earlier termination of sleep than young subjects. They also reported larger decreases in alertness and well-being and larger increases in sleepiness, weariness and effort required to perform daily functions. The rate of adjustment of the circadian core temperature rhythm to the new schedule did not differ between groups. These results suggest that the symptoms reported by the middle-aged subjects may be due mainly to difficulty maintaining sleep at early times of the circadian day. The compensatory response to sleep deprivation may also be less robust in middle-aged individuals traveling eastbound.

High nocturnal body temperature in premenstrual syndrome and late luteal phase dysphoric disorder

OBJECTIVE

Because women with late luteal phase dysphoric disorder (LLPDD) experience symptomatic affective states predictably, they can be studied to determine whether there are biological findings related solely to the clinically symptomatic state. The authors sought to answer the question, Does body temperature change with affective state?

METHOD

The core body temperature and motor activity patterns of 10 women with premenstrual syndrome (PMS), six of whom also met criteria for LLPDD, and no other psychological or medical illness were compared to those of six women with chronic, noncyclic dysphoria and six asymptomatic comparison women at four phases of the menstrual cycle.

RESULTS

The nocturnal temperatures of the women with PMS/LLPDD were significantly higher than those of the comparison subjects across the entire menstrual cycle, but there were no differences in nocturnal activity levels. The women with noncyclic dysphoria had a mean nocturnal temperature in the follicular phase as high as that of the women with PMS/LLPDD. The temperatures of all women were higher in the luteal phase than in the follicular phase.

CONCLUSIONS

These findings suggest that in the future investigators should document menstrual cycle phase in all female subjects and, when studying body temperature, should carefully monitor symptomatic state in comparison subjects.

Premenstrual syndrome

Because researchers are still seeking the cause of PMS, we cannot recommend a single treatment approach that will work satisfactorily with all women who have the syndrome. Investigators have made progress, however, toward defining and diagnosing the condition. We also can help women whose lives are disrupted each month by prescribing specific approaches to symptom management.

Circadian determinants of subjective alertness

Four healthy male subjects each experienced a temporal isolation experiment lasting several months. During part of each experiment (2-5 weeks), the subject's entire imposed daily routine (including light-dark, rest-activity, and meal routines) was either stretched (two subjects: T = 25.8 hr, 26.0 hr) or reduced (two subjects: T = 22.8 hr, 23.1 hr) to beyond the range of entrainment of the endogenous circadian pacemaker (ECP), which then ran at a different period (tau). Subjective alertness was measured approximately three times per hour (during wakefulness), using a computerized visual analogue scale technique. Circadian rhythms in subjective alertness were then plotted both at tau, the period length of the ECP, and at T, the period length of the imposed sleep-wake cycle (SWC) and light-dark cycle. At tau, the alertness rhythm was closely in phase with the temperature rhythm. At T, the alertness rhythm showed an "inverted-U" function with a peak toward the middle of the subjective day, upon which was superimposed a "postlunch dip" for one subject. Thus, subjective alertness would appear to be under the control fo both ECP and SWC mechanisms, which combine to produce the composite time-of-day function normally observed in a diurnal setting.

The timing of bedtime and waketime decisions in free-running subjects

Twelve "free-running" temporal isolation studies were performed using healthy human subjects aged 20-81 years (4 males, 8 females). Circadian rhythms were measured in subjective alertness (using a visual analogue scale technique) and rectal temperature. In all 12 subjects best fitting rhythm period were found to be shorter for rectal temperature (mean = 24.3 hours) than for subjective alertness (mean = 24.8 hours). Both rhythms were predictive of bedtime and waketime decisions. Bedtime decisions tended to cluster on the falling arm of the temperature and alertness cycles (modal times = 120 degrees (temperature) and 140 degrees (alertness) after acrophase); waketime decisions on the rising arm (modal times = 240 degrees (temperature) and 300 degrees (alertness) after acrophase). When this pattern was violated, sleep episodes were significantly more variable in length and disturbed by intruding wakefulness.

Removal of temporal constraints in the middle-aged and elderly: effects on sleep and sleepiness

Ten healthy middle-aged and elderly subjects (44-81 years old; 4 men and 6 women) were studied in time isolation experiments involving: (a) entrainment to the subject's habitual routine (EN condition) and (b) removal of all temporal constraints or "free-running" (FR condition) with the subjects able to choose their own bed and meal times. Subjective day lengths and circadian temperature cycle periods were longer under FR than under EN, but not by an equal amount. Perhaps as a consequence, although time-in-bed (TIB) fractions were greater under FR than under EN, actual sleep fractions were not, reflecting a decline in sleep efficiency. Neither was there an increase in slow-wave sleep (SWS) under FR compared with EN. Daytime subjective alertness did, however, increase upon release into FR, also showing a slightly earlier peak than that observed under the EN condition. The results point to the need to regard sleep and sleepiness as rhythmic, as well as homeostatic, processes.

Inducing jet lag in the laboratory: patterns of adjustment to an acute shift in routine

Eight middle-aged males were studied in a temporal isolation experimental lasting 15 d. After 5 d and nights of entrainment to his own habitual routine, each subject experienced an acute, unheralded 6-h phase advance in routine, accomplished by truncating his sixth sleep episode. For the remaining 10 d of the study, subjects were held to a routine 6-h phase advanced to the original. Significant symptoms of jet lag appeared in mood, performance efficiency, sleep, and circadian temperature rhythms. When plotted as a function to "days post-shift," some variables (temperature phase, percent rapid eye movement sleep) showed a fairly monotonic recovery to baseline levels. However, other variables (actual sleep duration, percent slow wave sleep, motivation loss, subjective sleepiness) showed a zig-zag recovery pattern, suggesting the interaction of two competing processes, and reinforcing the need for greater sophistication in the development of jet lag coping strategies.

Response of circadian locomotor activity and the proestrous luteinizing hormone surge to phase shifts of the light-dark cycle in the hamster

Female hamsters with regular 4 day estrous cycles were exposed to either a 3 hour phase advance or delay of the 14:10 light-dark (LD) cycle on the first, second or third day before proestrus. Blood samples were taken on proestrus to characterize the LH surge, and locomotor activity onset was recorded. Both the LH surge and activity onset phase delayed more quickly than they advanced, which can be explained by the free-running period of the hamster (longer than 24 hours). Higher estradiol levels were correlated with more rapid advances of activity onset.

Estrogen modifies the circadian timing and amplitude of the luteinizing hormone surge in female hamsters exposed to short photoperiods

LH surges occur 3 h later in intact anovulatory hamsters exposed to nonstimulatory photoperiods (6L:18D) for 8 wk than the proestrous LH surges from the same hamsters housed in 6L:18D for 3 weeks. In ovariectomized hamsters housed in 6L:18D for 3 wk, the LH surge was observed at the same time of day as in intact anovulatory hamsters at 8 wk. Implanting Silastic capsules containing estradiol benzoate (EB) advanced the timing of the daily surge of LH in ovariectomized hamsters housed in 6L:18D for 8 wk. EB also affected the magnitude of the LH surge in hamsters housed in 6L:18D for 8 wk. Two days after receiving EB implants, daily LH surges in anovulatory hamsters were suppressed by 75% and in ovariectomized "regressed" hamsters by 37%. This difference between groups was probably due to ovarian progesterone in intact animals. Estrogen is not required for LH surges in anovulatory hamsters but suppresses LH release when administered exogenously. The delay in the timing of the LH surge in anovulatory hamsters may result from the decline in estrogen resulting from short photoperiod exposure.

Human growth hormone release is decreased during sleep in temporal isolation (free-running)

Growth hormone (hGH) secretion was measured during sleep in 10 healthy male subjects isolated from all time cues. HGH concentrations following sleep onset were compared between scheduled sleep episodes (entrainment) and self-selected sleep episodes (free-running). Peak sleep-related hGH values were decreased significantly during free-running. The duration of the first slow wave sleep (SWS) episode and the latency to the first REM sleep episode also decreased significantly during free-running. The latencies from sleep onset to SWS and to peak hGH secretion did not differ between entrainment and free-running. These results suggest that sleep-related hGH secretion begins 'on time' during free-running, but is terminated earlier. Thus, while sleep onset facilitates hGH release, the timing of other stages of sleep such as REM may alter the magnitude of sleep-related hGH secretion.

Diurnal variation in mood and performance in a time-isolated environment

In order to document circadian rhythmicity in various psychological functions under the chronobiologically 'pure' condition of temporal isolation, a battery of mood and performance tests were administered about 6 times per day to a heterogeneous group of 18 subjects (ages 19-81, 5 female). Each subject spent about 5 days in temporal isolation, entrained to a routine equivalent to his/her own habitual sleep/wake cycle. Average time of day functions were obtained for the mood and performance variables, and compared to rectal temperature data subjected to exactly the same statistical analysis. Significant time of day effects were found in the mood variables of alertness, sleepiness, weariness, effort required, happiness and well-being. Times of 'best' mood were different from the time of peak temperature. Moreover, the minima of sleepiness, weariness and effort occurred earlier in the day than the maximum of alertness. Significant time of day effects were also found in the speed with which search and dexterity tasks were completed. Only the dexterity tasks showed a complete parallelism with the temperature rhythm.

Circadian rhythms in human performance efficiency under free-running conditions

A series of four experiments is described in which two men and two women (age range 22-79 years) were allowed to 'free-run' under conditions of isolation from all time cues. The circadian rhythms of performance efficiency were studied for three tasks: serial search, verbal reasoning, and manual dexterity (left and right hand versions). Strong evidence was obtained to suggest that different tasks are under the control of different circadian oscillators. The circadian rhythm in verbal reasoning performance tends to run at a shorter circadian period than that in more simple repetitive tasks, and slight differences in circadian behavior can occur between left- and right-handed dexterity.

Sex differences in circadian control of LH secretion

Sex differences in the hourly values of serum LH were examined in male and female Syrian hamsters exposed to either long photoperiods (14 h light: 10 darkness; 14L: 10D) or short photoperiods (6L: 18D). In long photoperiods, females exhibited a pro-oestrous surge of LH in response to high levels of circulating oestradiol (1047.36 +/- 90.68 pmol/l), while LH values in male hamsters remained essentially constant. In females housed in short photoperiods oestradiol levels were reduced by fivefold; however, a discrete surge in serum LH, similar to that seen at pro-oestrus in females exposed to long photoperiods, was observed. Although exposure to a short photoperiod eliminates the requirement of a positive feedback of oestrogen for the expression of an afternoon surge in LH, male hamsters housed in short photoperiods showed no indication of an afternoon surge in serum LH. These observations indicate that sex differences in the neural control of LH release are not the result of sex differences in oestrogen sensitivity or responsiveness.

Task variables determine which biological clock controls circadian rhythms in human performance

There are circadian (approximately 24 h) rhythms for a wide range of human physiological and psychological functions including mood and performance efficiency. These rhythms are self-sustaining in conditions of temporal isolation, indicating that internal oscillators (or biological clocks) control them. Recent research has proposed an endogenous two-oscillator model of the human circadian system, with one oscillator indicated by the core body temperature rhythm and a second oscillator responsible for the daily cycle of sleep and wakefulness. The present study was designed to produce a desynchronization in period between the two oscillators, to assess directly the behaviour of the rhythms of different performance tasks. The results, reported here, indicate that a simple manual dexterity task is almost entirely under the control of the temperature rhythm oscillator, whereas a more complex cognitive task demonstrates a periodicity which appears to be influenced by those oscillators controlling temperature and the sleep/wake cycle.

Chronobiology of aging: temperature, sleep-wake rhythms and entrainment

Studies were carried out on a group of six young (ages 23-30) and six older (ages 53-70) normal men who lived under conditions of temporal, but not social isolation, from three to eight weeks. During entrained and non-entrained (free-running) conditions, comparative measurements were made of sleep-wake cycles, sleep stages and rectal temperature rhythms for these two age groups. Results demonstrated a reduction in the period and amplitude of the body temperature rhythms during free-running in the older group. Sleep efficiency, total sleep time, REM sleep latency, REM episode length, percent REM in the last 2 hours of sleep, the length and frequency of arousals during sleep, and the terminal wake latency were all age related and dependent on entrainment. The period of the sleep-wake cycle, terminal awakenings from REM and percent REM in the first 3 hours of sleep were not age related but were dependent on entrainment. Sleep stages as percents of total sleep time were found to be age related but independent of entrainment, while sleep latency, mid-REM to mid-REM cycle length and the ratio of sleep to total time were neither age related nor dependent on entrainment. In addition, individual chronobiological differences were prominent in the older group. Changes of period and of the phase relationship of sleep-wake and temperature rhythms occurred in several subjects during the non-entrained condition.